:: Marijuana – Washington state, Colorado, and Oregon will all vote on whether to legalise the drug for recreational use and tax it. Washington looks likeliest to become the first US state to do so.

:: Same-sex marriage - Ballots are taking place on the issue in Maryland, Washington, Maine and Minnesota. Brad Pitt has donated $100,000 (£62,000) to those campaigning for same-sex marriage. In Maryland and Washington the ballot measures were brought by opponents seeking to repeal existing laws allowing same-sex marriage

:: Right to die – Massachusetts will vote on whether to allow terminally ill patients with less than six months to live to request drugs to end their lives.

:: GM Foods – California is voting on whether to require mandatory labelling on genetically modified foods sold in the state.